Conventionally, a vehicle display device as a head-up display device that projects an image on a windshield of a vehicle is provided in an instrument panel (for example, see Patent Literature 81). In a vehicle display device 8700 described in Patent Literature 81, an image projector 8701 arranged in an instrument panel I8000 projects an image on a windshield F8000 through an opening H8000 formed in a facing wall A8000 of the instrument panel I8000, the facing wall A8000 facing the windshield F8000, as illustrated in FIG. 79.